     {:optimizations :none
      :output-dir "out"
      :output-to "out/hello.js"
-     :source-map true})
-
-  (mapped-stacktrace
-    [{:file "cljs/core.js"
-      :function "first"
-      :line 2
-      :column 1}]
-    {:output-dir "out"})
-
-  (print-mapped-stacktrace
-    [{:file "cljs/core.js"
-      :function "first"
-      :line 2
-      :column 1}]
-    {:output-dir "out"})
+     :source-map true}
+    st)
+
+  (env/with-compiler-env st
+    (mapped-stacktrace
+      [{:file "cljs/core.js"
+        :function "first"
+        :line 2
+        :column 1}]
+      {:output-dir "out"}))
+
+  (env/with-compiler-env st
+    (print-mapped-stacktrace
+      [{:file "cljs/core.js"
+        :function "first"
+        :line 2
+        :column 1}]
+      {:output-dir "out"}))
   )
 
 (defn- display-error

           "(" file (when line (str ":" line)) (when column (str ":" column)) ")"))))))

(comment
  (cljsc/build "samples/hello/src"
    {:optimizations :none
     :output-dir "samples/hello/out"
     :output-to "samples/hello/out/hello.js"
     :source-map true})

  (mapped-stacktrace
    [{:file "hello/core.js"
      :function "first"
      :line 2
      :column 1}]
    {:output-dir "samples/hello/out"})

  (print-mapped-stacktrace
    [{:file "hello/core.js"
      :function "first"
      :line 2
      :column 1}]
    {:output-dir "samples/hello/out"})

  ;; URL example


               (some-> (js-src->cljs-src f) ana/parse-ns :ns))]
      (when ns
        (as-> @env/*compiler* compiler-env
          (let [t (util/last-modified smf)]
            (if (or (and (= ns 'cljs.core)
                         (nil? (get-in compiler-env [::source-maps ns])))
                    (and (not= ns 'cljs.core)
                         (> t (get-in compiler-env [::source-maps ns :last-modified] 0))))
              (swap! env/*compiler* assoc-in [::source-maps ns]
                {:last-modified t
                 :source-map (sm/decode (json/read-str (slurp smf) :key-fn keyword))})
              compiler-env))
          (get-in compiler-env [::source-maps ns :source-map]))))))

(defn ns-info
  "Given a path to a js source file return the ns info for the corresponding
